Using different selection criteria for lung cancer screening may catch more disease than the currently recommended criteria, researchers found.

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Using different selection criteria for lung cancer screening may detect more disease than the currently recommended criteria.

Point out that the model used incorporated factors such as level of education, family history of lung cancer, and COPD status.

Using different selection criteria for lung cancer screening may catch more disease than the currently recommended criteria, researchers found.

A modified model from the Prostate, Lung, Colorectal, and Ovarian (PLCO) trial had a significantly better positive predictive value than criteria from the National Lung Screening Trial (NLST) -- 4% versus 3.4%, P=0.01 -- without a loss of specificity, Martin Tammemagi, PhD, of Brock University in St. Catharines in Ontario, and colleagues reported.

"The wide gap in the ability to predict lung cancers between the NLST and PLCO criteria should translate into more efficient selection for screening, greater cost-effectiveness, and additional lives saved from low-dose CT screening," they wrote in the Feb. 21 issue of the New England Journal of Medicine.

Results of the NLST showed that lung cancer screening with low-dose CT reduced lung cancer mortality by 20%. Some physician groups, including the American Cancer Society, have started to recommend screening based on the criteria used in that trial -- patients ages 55 to 74 who have at least a 30-pack-year smoking history and either still smoke or have quit within the last 15 years.

But some specialists have raised concerns that those parameters exclude many patients at risk for lung cancer.

"The way the criteria were established for the NLST was not based on scientific fact. They were trying to come up with criteria that would result in a positive study ... and rightfully so," Dan Raz, MD, surgical director of the lung cancer and thoracic oncology program at City of Hope Hospital in Duarte, Calif., told MedPage Today. "That doesn't mean that's where screening should stop."

Some argue that taking additional risk factors into account may catch more patients at risk for lung cancer. That's what the PLCO trial did, adding such factors as level of education, family history of lung cancer, and COPD status, in addition to history and duration of smoking and quit time.

It had good predictive discrimination, the researchers said, but can be "cumbersome to apply" -- so they modified it and applied it to NLST data.

They found that their modified PLCO criteria still had good predictive discrimination with an area under the curve of 0.803 for smokers in the control group and 0.797 for smokers in the intervention group.

Compared with NLST criteria, they found that the new PLCO criteria had significantly improved sensitivity (83% versus 71.1%, P<0.001) for detecting lung cancers as well as the significantly better positive predictive value.

And those gains were accomplished without a loss of specificity (62.9% and 62.7%, respectively).

The new PLCO model found 81 more patients for screening who ended up having a diagnosis of lung cancer who were not caught by NLST criteria. Ultimately, 41.3% fewer lung cancers were missed, the researchers noted.

"The model based on the PLCO is a very important step toward helping refine the criteria to better identify people at risk for lung cancer so we can screen them in a more efficient way," Raz said.

He added that his facility relies on National Comprehensive Cancer Network recommendations for screening, which liberalize smoking requirements -- to 20 pack-years instead of 30 -- and include patients as young as 50 instead of 55 who have additional risk factors such as an occupational exposure or a strong family history.

Raz also said it's likely that any official recommendations from the U.S. Preventive Services Task Force, which is currently evaluating lung cancer screening guidelines, will reflect the criteria set by the NLST.

However, he said, "other data from other screening trials such as the ELCAP study ... would be very useful to try to broaden the criteria for lung cancer risk so that we can screen people more effectively."

The PLCO trial was supported by the National Cancer Institute.

The researchers reported no relevant conflicts of interest.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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